Subgenus Stenosmia

Stenosmia Michener was formerly treated as a genus (Michener, 2007; Ungricht et al., 2008). However, in a recent molecular phylogeny of the osmiine bees (Praz et al., 2008b), Stenosmia was found to branch off from within the genus Hoplitis. Therefore, Stenosmia is treated here as a subgenus of Hoplitis. Stenosmia is confined to the Palaearctic region. It contains 13 described species.

Identification-Keys, Descriptions: Zanden (1992c: 824); Müller (2014b: 314-315). As revealed by a large sample of H. aravensis collected in southwestern Iran in spring 2014 by S. Falamarzi, variation in body length is larger than hitherto assumed (Müller, 2014b): body length of females is 4.5-7mm and that of males is 4-5.5mm. In addition, the small hair patch on sternum 6 typical for males of H. aravensis (Müller, 2014b) is very inconspicuous in some individuals.

Nesting biology: Unknown.

Flower preferences: Probably oligolectic on Tamarix (Tamaricaceae) (based on Müller (2014b) and S. Falamarzi (personal communication), who observed large numbers of pollen-collecting females and nectar-sucking males on Tamarix flowers at two localities in southwestern Iran in March 2014).

Identification-Keys, Descriptions: Zanden (1985: 68). Misapplication: The assignment of Hoplitis brunnescens (Benoist, 1950) to the subgenus Hoplitis by Warncke (1992a) is erroneous. The investigation of the female holotype revealed that H. brunnescens belongs to the subgenus Stenosmia and that the type specimen is probably conspecific with H. tagmouta (Warncke, 1991). However, the type slightly differs from typical females of H. tagmouta by the longer vertex and the reddish colour of legs and terga 1-3 (partly also of terga 4 and 5), rendering a synonymization premature. Only further material including males will show whether H. brunnescens and H. tagmouta are conspecific or represent two distinct species.

Identification-Keys, Descriptions: No supplementary or more detailed morphological description known.

Nesting biology-Nesting site: In excavated burrows in sandy soil. Colonies consisting of 5-20 nests have been found in sandy desert areas on takyr soil. The nests consist of a main burrow that ramifies into two or three side burrows. The brood cells, which are built at the end or at the side of these burrows at a depth of 3.5-7cm, open directly into the burrrow. Nesting material: The cells are closed with soil. The walls of burrows and brood cells consist of compressed soil, they are not lined with foreign material. (Marikovskaya, 1968, as Osmia flavicornis)

Flower preferences: Probably oligolectic on Frankenia (Frankeniaceae) (based on Müller (2014b) and on field observations in southern Morocco in April 2017, where females were observed to collect pollen on Frankenia laevis).

Flower preferences: Oligolectic on Zygophyllaceae; one pollen load consisted of pollen of Brassicaceae, suggesting that flowers of this plant family might occasionally be exploited as well (Müller, 2014b).

Nesting biology-Nesting site: In excavated burrows in sandy soil. An aggregation of about 20 nests was found on an area of roughly 3 square metres in southern Morocco near Sidi Ifni in April 2017. The nest entrances were all located on bare sandy soil between small shrubs of Frankenia laevis. Nesting material: Several females were observed to collect soil on the ground and to transport it over a distance of 10-15cm into their nests, suggesting that the walls of the brood cells and/or the walls of the nesting burrows are lined with soil. Interestingly, the females did not collect dry sand but instead harvested moister earth, which they found at the shaded base of Frankenia plants or in small soil crevices. (A. Müller, unpublished)

Flower preferences: Most probably oligolectic on Frankenia (Frankeniaceae) (based on Müller (2014b), on 11 pollen loads from 2 different localities, on the content of 3 brood cells and on field obervations). The males were observed to patrol both the flowers of Frankenia laevis and the nest entrances in their search for females; they regularly interrupted their patrolling flights by short resting periods on the ground (A. Müller, unpublished).

Nesting biology-Nesting site: In excavated burrows in sandy soil. A single nest was found in southern Morocco near Sidi Ifni in April 2017; its entrance was located on bare sandy soil. Nesting material: Unknown. (A. Müller, unpublished)